The formula for calculating the speed of the mouse's horizontal motion is the absolute value of the difference between mouseX and pmouseX. The absolute value of a number is defined as that number without its sign: The absolute value of -2 is 2. The absolute value of 2 is 2. In Processing, you can get the absolute value of the number by placing it inside the abs () function, that is abs (-5) equals 5. The speed at which the mouse is moving is therefore float mouseSpeed abs (mouseX pmou sex); - Fill in the blank below and then try it out in Processing! stroke(e); Line(pmousex, pmouseY, mousex, mouseY)